A user on TV.com suggested, just after episode four of season eight aired, that Dr. Evelyn Vogel killed Harry Morgan.
Abo_Malek’s main argument is that law enforcement generally use firearms to commit suicide, rather than overdosing, as Harry does on his heart medication.
I must preface my response with the fact that I understand that this user was projecting their ideas at the time that the fourth episode was aired, and so they did not have enough information regarding Vogel at this point in time, nor had we seen Dr. Vogel’s full character arc.
Because Hannah McKay, the poisonous female (in every sense of the word) antagonist, was a key component of season seven, I am inclined to believe that the writers of Dexter would not impute the same modus operandi in the following season. We do not have concrete proof of Abo_Malek’s point; however, we do have experience with crooked therapists. Dexter’s target in “Shrink Wrap” (S1E8), Dr. Emmett Meridian, pushed his powerful female clients to suicide when they were most vulnerable. While this was Dr. Meridian’s way of channeling his own Dark Passenger, Evelyn Vogel’s own dark curiosities (we can even call it her Dark Passenger) were further displaced. She compelled Harry to teach Dexter to kill by the Code, rather than counselling Dexter directly.
If we assume that Dr. Vogel pulled a “Dr. Meridian” on Harry by compelling him to kill himself, this would befit the situation that unfolds in that Vogel is willing, and desires, to step in as his mother figure, and the only way to do so was by eliminating the middleman.
Vogel is a known scholar in sociopathic and psychopathic behavior; her Frankenstein-esque curiosity and passion for her vocation complicates this user’s idea. Harry is virtually her only way to accessing Dexter and his psyche. She is well aware of Harry and Dexter’s profound level of trust and is too wise to believe that she could step in, at the time of Harry’s suicide, and pick up where his foster father left off. Although she wants nothing more than to observe her “creation” up close and personally, eliminating Harry effectively forces Dexter to live inwardly and trust no one. It would be ridiculous for her to believe that Dexter would seek another form of connection beyond his father, for she believes Dexter is a psychopath in every sense of the word, meaning that, characteristically, he does not actively seek human connection.
There is, of course, the possibility that once Harry evinced his unreliability, Vogel could not take the chance in keeping him alive, allowing him to possibly go on to tell someone of their unorthodox therapy sessions. Perhaps she saw him as a liability.
In a way, Vogel indirectly killed Harry through her recommendations; however, I am not entirely convinced that Vogel offed Harry herself. If she did, I don’t think she would keep the videos of their sessions, which could later incriminate her if they ever got into the wrong (or right) hands. As a therapist, she has the legal obligation to forego confidentiality if one of her patients poses a threat to either himself or others (I believe this applies whether or not they are formal sessions).
To read Abo_Malek’s argument in full, click the above image.